Isolated LV Non-Compaction Controversies in Diagnostic Criteria
Isolated LV Non-Compaction Controversies in Diagnostic Criteria
Isolated left ventricular non-compaction (LVNC) is a morphological abnormality of excessive trabeculation of the LV, often complicated by ventricular dysfunction, arrhythmias and cardioembolism. Advances in cardiovascular imaging and widespread availability of imaging technology have led to an increase in the diagnosis of LVNC imposing a need for evidence-based imaging diagnostic criteria. Although recent studies have addressed the utility of newer diagnostic methodologies and the incidence of adverse events in this condition, the diagnosis and management remain controversial. In this review, we provide an overview of the current controversies in the clinical diagnosis of LVNC, and suggest a management approach.
Isolated left ventricular non-compaction (LVNC) is a myocardial disorder characterised by prominent ventricular trabeculations and deep recesses extending from the LV cavity to the subendocardial surface of the LV wall with or without LV dysfunction. LVNC can be diagnosed in childhood or only recognised later in life. In childhood, the classic description of a distinctive 'non-compacted' spongy appearance of the myocardium was associated with congenital heart diseases in earlier literature, but has been identified as a distinct entity over the past few decades. When the disease is first recognised later in life, it is often not clear whether this represents late recognition of long-standing non-compaction or delayed morphological manifestation of an underlying cardiomyopathy. Association between LVNC and neuromuscular disorders has also been demonstrated.
Although the American Heart Association has classified LVNC as a primary genetic cardiomyopathy, the European Society of Cardiology refers to LVNC as an 'unclassified cardiomyopathy' based on the fact that LVNC may be a morphological manifestation of several distinct cardiomyopathies. At present, there is no consensus on whether LVNC is a distinct cardiomyopathy, an epiphenomenon or a phenotypic variant of other cardiomyopathies. However, the absence of specific genotype-phenotype association, the occurrence of LVNC morphology in various metabolic diseases and other cardiomyopathies, and the illustration that the LVNC phenotype is not necessary for development of cardiomyopathy, all suggest that it is unlikely a distinct cardiomyopathy.
Advances in cardiovascular imaging and its widespread availability have led to increased diagnosis of LVNC. However, there exists poor agreement between the various diagnostic criteria with a preponderance towards overdiagnosis. The field is further challenged by rarity of the disease, the publication of only small studies, the lack of international/multicentre collaborations, and the absence of a non-pathological gold standard for diagnosis. Furthermore, since older case series were affected by limitations in imaging techniques and the use of evidence-based therapies, patients were generally diagnosed with advanced disease and had more adverse outcomes. In this paper, using a structured literature search, we provide a comparison of the different imaging-based diagnostic criteria along with discussion of newer approaches, provide an update to the adverse outcome data with comparison of older and newer studies, and suggest a management approach for patients with LVNC. Other recent publications have provided a comprehensive review of the epidemiology, pathogenesis, genetic considerations, clinical presentation and natural history of LVNC, and are, hence, not discussed in this review.
Abstract and Introduction
Abstract
Isolated left ventricular non-compaction (LVNC) is a morphological abnormality of excessive trabeculation of the LV, often complicated by ventricular dysfunction, arrhythmias and cardioembolism. Advances in cardiovascular imaging and widespread availability of imaging technology have led to an increase in the diagnosis of LVNC imposing a need for evidence-based imaging diagnostic criteria. Although recent studies have addressed the utility of newer diagnostic methodologies and the incidence of adverse events in this condition, the diagnosis and management remain controversial. In this review, we provide an overview of the current controversies in the clinical diagnosis of LVNC, and suggest a management approach.
Introduction
Isolated left ventricular non-compaction (LVNC) is a myocardial disorder characterised by prominent ventricular trabeculations and deep recesses extending from the LV cavity to the subendocardial surface of the LV wall with or without LV dysfunction. LVNC can be diagnosed in childhood or only recognised later in life. In childhood, the classic description of a distinctive 'non-compacted' spongy appearance of the myocardium was associated with congenital heart diseases in earlier literature, but has been identified as a distinct entity over the past few decades. When the disease is first recognised later in life, it is often not clear whether this represents late recognition of long-standing non-compaction or delayed morphological manifestation of an underlying cardiomyopathy. Association between LVNC and neuromuscular disorders has also been demonstrated.
Although the American Heart Association has classified LVNC as a primary genetic cardiomyopathy, the European Society of Cardiology refers to LVNC as an 'unclassified cardiomyopathy' based on the fact that LVNC may be a morphological manifestation of several distinct cardiomyopathies. At present, there is no consensus on whether LVNC is a distinct cardiomyopathy, an epiphenomenon or a phenotypic variant of other cardiomyopathies. However, the absence of specific genotype-phenotype association, the occurrence of LVNC morphology in various metabolic diseases and other cardiomyopathies, and the illustration that the LVNC phenotype is not necessary for development of cardiomyopathy, all suggest that it is unlikely a distinct cardiomyopathy.
Advances in cardiovascular imaging and its widespread availability have led to increased diagnosis of LVNC. However, there exists poor agreement between the various diagnostic criteria with a preponderance towards overdiagnosis. The field is further challenged by rarity of the disease, the publication of only small studies, the lack of international/multicentre collaborations, and the absence of a non-pathological gold standard for diagnosis. Furthermore, since older case series were affected by limitations in imaging techniques and the use of evidence-based therapies, patients were generally diagnosed with advanced disease and had more adverse outcomes. In this paper, using a structured literature search, we provide a comparison of the different imaging-based diagnostic criteria along with discussion of newer approaches, provide an update to the adverse outcome data with comparison of older and newer studies, and suggest a management approach for patients with LVNC. Other recent publications have provided a comprehensive review of the epidemiology, pathogenesis, genetic considerations, clinical presentation and natural history of LVNC, and are, hence, not discussed in this review.
